Almost all of the files under chainstate are touched frequently, but I have a handful that are unchanged since the initial sync months ago. These files start with 0, unlike the recent ones that start with 6.
Are the 0 files still in use, or are they leftovers that weren't automatically deleted?
Is it a full node or a pruned node?
Weird in my opinion... it should all have a "last modified" date of the latest time you opened your client, or at least that seems to be the case with my folder.
The only 2 files that aren't "last modified" on the latest time I opened the client are "LOG" and "LOG.old" which are from last september.
In case of doubt, just delete the entire chainstate folder and get a new fresh one by just opening the client.